Washington: American billionaire investor Warren Buffett has been diagnosed with stage I prostate cancer, the CNN reported.

In a letter to shareholders of his firm Berkshire Hathaway, Buffett, 81, said Tuesday his "condition is not remotely life-threatening or even debilitating in any meaningful way".

He said additional tests did not reveal incidence of cancer anywhere else in his body.

"I feel great -- as if I were in my normal excellent health -- and my energy level is 100 percent," Buffett wrote.

Over 70 percent of men diagnosed with prostate cancer do not die from the disease, according to Otis Brawley, a prostate cancer expert.

Buffett said he will undergo daily radiation for two months beginning in mid-July, a decision made with his doctors.

Buffett has made a name for himself by turning Berkshire Hathaway into a successful investment firm. Berkshire owns more than 80 companies, including insurer Geico, chemical company Lubrizol, railroad company Burlington Northern Santa Fe, and MidAmerican Energy.

Buffett has yet to name his successor as CEO of Berkshire.